Charles, there is no doubt that now days more and more vehicles are equipped with natural gas tanks and fuel injection system due to various reasons. I think the major advantage with natural gas is its less pollution level and cost effectiveness.
Mydesign, You are correct. Many vehicles could be modified to run on natural gas. I have a friend who has traveled extensively in Asia and found lots of natural gas powered vehicles there. There are also lots in South America. My understanding from him is that they have longer range. I am not sure of how that is compared.
As Chuck said, most of thevehicles we will see are trucks. In Chicago a large concrete company has said that all of its trucks are being replaced with natural gas burning vehciles by 2020 (I think). They have already started to deploy. The company is Ozinga and they have over 500 vehicles.
One of the big impacts of using natural gas in large trucks is that they tend to use a lot more fuel than the average automobile. That should have an outsized impact on oil usage here.
"Many vehicles could be modified to run on natural gas. I have a friend who has traveled extensively in Asia and found lots of natural gas powered vehicles there. '
Naperlou, in our country, for a particular state all the public transport vehicles are using CNG (Compressed Natural Gas) and state government insisted all private vehicles to convert the mode of fuel as CNG. Federal government also has a plan to make it compulsory from 2016.
Agreed, mydesign. Natural gas pollutes less, whih is a big advantage. The downsides are the initial vehicle cost is a little higher, energy density is lower, and natural gas, for some reason, is not very compatible with the new higher-tech, direct injection systems.
Natural gas causes less pollution, is much more cheaper than petroleum and saves travel cost by a good margin. However, it is necessary that ample natural gas resource be present if the shift is under consideration.
@naperlou - I'm from South Asia so I can affirm to that. Most vehicles ranging from trucks down to the conventional taxi cab runs on natural gas over here and even though we have a rich natural gas resource over here, the overwhelming number of vehicles has caused a supply shortage resulting in crises.
@Charles - There is definitely performance degradation on natural gas, however there is increased efficiency due to cheaper cost. Another downside though, is that, there is a gas cylinder which takes up a lot of space when natural gas is used as a secondary fuel source.
Charles, if am not wrong, these natural gases are one of the purest forms of gasoline in gaseous stage. Then I would like to know what's the difference between the LPG (liqudified petroleum Gas – cooking gas) and natural gases.
I don't know much about LPG, mydesign, but I'll tell you what I know and maybe our readers can add to it. Natural gas is essentially methane, whereas liquefied petroleum (propane and butane) is a hydrocarbon-based gas. It is used in automobiles, but its energy density is lower than that of gasoline, so its fuel consumption is higher. As for a comparsion of emissions -- I'll leave that to any of our smart readers who want to chime in.
Right now the big advantage of CNG is cost. Smog emission are 20% to 45% lower and Green House gas emissions are 5% to 9% lower on an equivalent basis. The equivalent cost per gallon is about $1.00+ less.
CNG (Compressed Natural Gas) can be successful in small vehicles. Honda has a CNG version of the Civic. However it's only available in California. The driving range is about 190 miles.
The overall operation is similar to LPG even though LPG contains 2.44 times as much energy per cubic foot. Since much of LPG is made from Natural Gas, there is no cost advantage. Even though LPG is a liquid, reasonable range is still provided by CNG due to the higher storage pressures used.
An alternative is to use LNG (Liquefied Natural Gas) This improves the range issue compared to CNG. The availability of this technology has helped drive the recent move to Natural Gas as a vehicle fuel. However the big deal is still cost.
"Natural gas is essentially methane, whereas liquefied petroleum (propane and butane) is a hydrocarbon-based gas. It is used in automobiles, but its energy density is lower than that of gasoline, so its fuel consumption is higher."
Murray, thanks for the clarification and I think you are right.
Hello My Design--Basically, natural gas is methane. Generally 84 to 90 % methane with a heating value ranging from 900 to 1200 Btu/Ft^ 3. LPG is classified as propane or butane. Propane has a heating value of approximately 2500 Btu/Ft^3 where as butane is 3500 Btu/Ft^3. In climates experienced in the United States, butane is not that suitable for most usage. Propane is the LPG of choice. Hope this helps.
Bobjengr, thanks for your clarification. I think most of our readers may have same doubt, when reading an article with respect to natural gas/CNG/LPG. I hope the response from our various members will help them to clarify it.
I have travelled to Korea (south of course) fairly often and they stand out as an example of how this fuel integrates into a country. They have widespread fueling stations for both gasoline and LP (not sure if LP or CNG). To the average consumer, using either is not an issue. However, it appears that the use of LP is more widespread in taxis than regular drivers.
That being said, they have a whole different dynamic than here in the US. Korea is much smaller than the US (about 300 miles will get you the whole way across the country). People don't have to drive as far or as much. Public transportation (train, bus, taxi, etc...) is widely utilized.
I found out on one trip that there are considerations when in a place that LP is used. A co-worker and I could not fit ourselves and our luggage into a standard sized taxi that ran LP. The driver had us use another taxi that looked the same, but was gasoline powered. Everything fit fine in it.
There are quite a few differences betwen using Liquid Propane (LP), and using natural gas (CNG). LP gas is stored as a liquid at around 300PSI, depending on the ambient temperature, while CNG must be kept at a much higher pressure since it is a gas, not a liquid. Both are used in the engine at a quite low pressure, so there is a lot of cooling as the pressure drops. LP regulators often include an arrangement to use hot engine coolant to prevent them from freezing, but I don't think that is needed for CNG regulators.
Direct injection is an interesting concept that might work well with CNG since the pressure is quite high, but manifold injection is probably the only other option with LP gas, due to it's lower pressure.
The real challenge would be in the logistics of refueling, since we have gasoline stations on half of our street corners, while LP refueling stations are much less common. Of course the 25 pound propane tanks do seem to be available at most corner stores, but it is not clear to me that a tank that size would provide enogh miles to make it a good choice. Also, I don't know if any of those stores accept trades, or do they just sell filled tanks?
The other very real challenge is the competence level of many people as far as being able to connect the tank without allowing a major leak. There is a whole class of folks who cross-thread lightbulbs and garden hoses, and I doubt that they would be able to connect a filling hose without allowing a lot of leakage. So there is a challenge that would need some real innovation to solve.
The busses in Fort Worth run on CNG. They do have a heat exchanger mounted on the side of the buss to re-heat the CNG before feeding it to the engine. They have huge tanks on top of the buss and have to fill up every 2 hours. It's still economical compared to gasoline and the required maintenance is somewhat less due to the cleaner fuel.
OK, so I may have been a bit off about needing to heat the CNG before using it. The busses have a real advantage in that they have a bus-barn to refuel at and a special person, or crew, to do the refueling. Do you have any idea about the capacity of those fuel tanks?
Direct injection is an interesting concept that might work well with CNG since the pressure is quite high
LP gas is stored as a liquid at around 300PSI
The pressure for CNG in the tank is about 200 atm (14*200 = 2800 PSI).
Usuall pressure in engine is about 12-16 atm (160-260 PSI).
So I don't beleive that direct injection of CNG is practical. However make use of the higher pressure for gas enabled (LPG & CNG) vehicales could be the option.
The technical challenge in this case is how to combile the gas (higher pressure) and gasoline injection in single engine. Most of the cars has two tanks: one for usuall gasoline and another for CNG/LPG.
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